As someone who's colorblind, I'm grateful for blue links. The worst are pages where the links are red and they've turned off the underscore--I have to drag the mouse all over the page to see where the pointer changes so I can find them. :)

I wrote a quick userscript for you:

    colorLinks("blue");
    
    function colorLinks(hex)
     {
      var links = document.getElementsByTagName("a");
      for(var i=0;i
Will make all links blue and underlined.

You can use this tool to convert it into a handy bookmarklet: https://caiorss.github.io/bookmarklet-maker/

Alternatively, you can paste it into the JS console, or install it with an extension like greasemonkey.

Hope this helps!

This is more easily, faster and better done as a user stylesheet:

  a {
      color: blue !important;
      text-decoration: underline !important;
      text-decoration-style: solid !important;
      text-decoration-color: blue !important;
  }
(Unfortunately, extensions like Stylus <https://github.com/openstyles/stylus> don’t handle user stylesheet priorities correctly: !important in a user stylesheet should override absolutely all site stylesheets, including inline style attributes. But because of lousy technical limitations, they load stylesheets at the site priority rather than the user priority. But then, what you presented doesn’t conquer a site !important spec anyway. See https://wattenberger.com/blog/css-cascade#origin for a really good explanation of all this stuff.)